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Tailoring adhesion of anionic surfaces using cationic PISA-latexes – towards tough nanocellulose materials in the wet state
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.ORCID iD: 0000-0002-9572-6888
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.ORCID iD: 0000-0003-4388-8970
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.ORCID iD: 0000-0001-8622-0386
Université de Lyon, Univ Lyon 1, CPE Lyon, CNRS UMR 5265, C2P2 (Chemistry, Catalysis, Polymers & Processes), LCPP, 69616 Villeurbanne, France .
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2019 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, p. 4287-4302Article in journal (Refereed) Published
Abstract [en]

Cationic latexes with Tgs ranging between −40 °C and 120 °C were synthesised using n-butyl acrylate (BA) and/or methyl methacrylate (MMA) as the core polymers. Reversible addition–fragmentation chain transfer (RAFT) combined with polymerisation-induced self-assembly (PISA) allowed for in situ chain-extension of a cationic macromolecular RAFT agent (macroRAFT) of poly(N-[3-(dimethylamino)propyl] methacrylamide) (PDMAPMA), used as stabiliser in so-called surfactant-free emulsion polymerisation. The resulting narrowly distributed nanosized latexes adsorbed readily onto silica surfaces and to model surfaces of cellulose nanofibrils, as demonstrated by quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. Adsorption to anionic surfaces increased when increasing ionic strength to 10 mM, indicating the influence of the polyelectrolyte effect exerted by the corona. The polyelectrolyte corona affected the interactions in the wet state, the stability of the latex and re-dispersibility after drying. The QCM-D measurements showed that a lower Tg of the core results in a more strongly interacting adsorbed layer at the solid–liquid interface, despite a comparable adsorbed mass, indicating structural differences of the investigated latexes in the wet state. The two latexes with Tg below room temperature (i.e. PBATg-40 and P(BA-co-MMA)Tg3) exhibited film formation in the wet state, as shown by AFM colloidal probe measurements. It was observed that P(BA-co-MMA)Tg3 latex resulted in the largest pull-off force, above 200 m Nm−1 after 120 s in contact. The strongest wet adhesion was achieved with PDMAPMA-stabilized latexes soft enough to allow for interparticle diffusion of polymer chains, and stiff enough to create a strong adhesive joint. Fundamental understanding of interfacial properties of latexes and cellulose enables controlled and predictive strategies to produce strong and tough materials with high nanocellulose content, both in the wet and dry state.

Place, publisher, year, edition, pages
2019. Vol. 11, p. 4287-4302
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-241447DOI: 10.1039/C8NR08057GISI: 000465410200012Scopus ID: 2-s2.0-85062644682OAI: oai:DiVA.org:kth-241447DiVA, id: diva2:1281449
Note

QC 20190123

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-05-29Bibliographically approved
In thesis
1. Tailored adhesion of PISA-latexes for cellulose modification and new materials
Open this publication in new window or tab >>Tailored adhesion of PISA-latexes for cellulose modification and new materials
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is focused on applying modification chemistry to already known cellulosic substrates from wood (i.e. cellulose nanofibrils, CNFs, and cellulose nanocrystals, CNCs). The modification is needed to overcome the drawbacks with the nanocellulosics alone, such as sensitivity to water (hydrophilicity) and the brittle material properties (however great stiffness). The first aim is to incorporate nanocellulosics into hydrophobic degradable materials of poly(ε-caprolactone) (PCL), resulting in aggregation if not modified. The challenge is to reach high fraction of nanocellulosics, whilst maintaining the flexibility of PCL and improving the properties of the resulting nanocomposite with the corresponding stiffness of the nanocellulosics. The second aim is to increase toughness and strain-at-break for nanocomposite materials of CNF-networks, to increase the plastic deformation equivalent of fossil-based polymeric materials such as polypropylene (PP). Aiming to achieve these goals, the thesis also includes new synthetic strategies of tailored-made set of block copolymers as modifying components. The modifying components, were synthesised by surfactant-free emulsion polymerisation and polymerisation induced self-assembly (PISA), so called PISA-latexes.

Two types of cationic polyelectrolytes, (poly(2-dimethylaminoethy methacrylate) (PDMAEMA) and poly(N-[3-(dimethylamino)propyl] methacrylamide (PDMAPMA)), being the corona of the latex, were synthesised. Followed by chain-extension with different hydrophobic monomers such as methyl methacrylate and butyl methacrylate, making up the core polymer of the resulting PISA-latex. The cationic PISA-latexes show narrow size distributions and the glass transition (Tg) of the core polymer can be varied between -40 °C to 150 °C. The PISA-latexes show strong adhesion to silica and cellulose surfaces as assessed by quartz crystal microbalance (QCM-D). Results also indicate that latexes with Tg below room temperature, considered soft, behave different in the wet state than latexes with Tg above room temperature, considered rigid. The softer latexes form clusters (visualised by imaging with microscopy and atomic force measurements (AFM)) and undergo film formation in the wet state. The latter, shown by colloidal probe measurements using AFM resulting in very large work of adhesion and pull-off forces.

The PISA-latexes compatibilize CNCs and different CNFs with PCL as a matrix polymer, observed by a small increase in stiffness for the final nanocomposites, however not at a level expected by rule-of-mixtures. The promising wet feeding technique results in large increase in stiffness but maintain PCL’s flexibility, above 200% strain-at-break, which is rarely observed for CNF-reinforced nanocomposites. The, in this case, rigid latex facilitate the dispersion of CNFs in the matrix without aggregation, until finally coalescing after processing and possibly giving rise to improved adhesion between CNF and the latex in the matrix, indicated by rheology measurements. Lastly, new nanocomposite films consisting of 75wt% CNF and 25wt% of PISA-latexes were produced and evaluated. The results show that CNF and rigid 100 nm sized PISA-latex, with PMMA core, gives a very tough double network, with strain-at-break above 28%, stiffness of 3.5 GPa and a strength of 110 MPa. These are impressive properties compared to commonly used fossil-based plastic materials.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2019. p. 128
Series
TRITA-CBH-FOU ; 2019:7
Keywords
PISA, latex, RAFT, Cellulose Nanofibrils, Cellulose Nanocrystals, Nanocomposites
National Category
Polymer Chemistry
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-241463 (URN)978-91-7873-086-5 (ISBN)
Public defence
2019-02-22, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20190123

Available from: 2019-01-23 Created: 2019-01-22 Last updated: 2019-05-20Bibliographically approved
2. Design of Cellulose-based Materials by Supramolecular Assemblies
Open this publication in new window or tab >>Design of Cellulose-based Materials by Supramolecular Assemblies
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Due to climate change and plastic pollution, there is an increasing demand for bio-based materials with similar properties to those of common plastics yet biodegradable. In this respect, cellulose is a strong candidate that is already being refined on a large industrial scale, but the properties differ significantly from those of common plastics in terms of shapeability and water-resilience.

This thesis investigates how supramolecular interactions can be used to tailor the properties of cellulose-based materials by modifying cellulose surfaces or control the assembly of cellulose nanofibrils (CNFs). Most of the work is a fundamental study on interactions in aqueous environments, but some material concepts are presented and potential applications are discussed.

The first part deals with the modification of cellulose by the spontaneous adsorption of xyloglucan or polyelectrolytes. The results indicate that xyloglucan adsorbs to cellulose due to the increased entropy of water released from the surfaces, which is similar to the increased entropy of released counter-ions that drives polyelectrolyte adsorption. The polyelectrolyte adsorption depends on the charge of the cellulose up to a limit after which the charge density affects only the first adsorbed layer in a multilayer formation.

Latex nanoparticles with polyelectrolyte coronas can be adsorbed onto cellulose in order to prepare hydrophobic cellulose surfaces with strong and ductile wet adhesion, provided the glass transition of the core is below the ambient temperature.

The second part of the thesis seeks to explain the interactions between different types of cellulose nanofibrils in the presence of different ions, using a model consisting of ion-ion correlation and specific ion effects, which can be employed to rationally design water-resilient and transparent nanocellulose films. The addition of small amounts of alginate also creates interpenetrating double networks, and these networks lead to a synergy which improves both the stiffness and the ductility of the films in water.

A network model has been developed to understand these materials, with the aim to explain the properties of fibril networks, based on parameters such as the aspect ratio of the fibrils, the solidity of the network, and the ion-induced interactions that increase the friction between fibrils. With the help of this network model and the model for ion-induced interactions, we have created films with wet-strengths surpassing those of common plastics, or a ductility suitable for hygroplastic forming into water-resilient and biodegradable packages. Due to their transparency, water content, and the biocompatibility of cellulose, these materials are also suitable for biomaterial or bioelectronics applications. 

Abstract [sv]

På grund av klimatförändringar och ständigt ökande plastföroreningar finns det en växande efterfrågan på biobaserade material med egenskaper som liknar dem hos vanliga plaster och som samtidigt är biologiskt nedbrytbara. I detta avseende är cellulosa är en stark kandidat som redan framställs i stor industriell skala, men egenskaperna skiljer sig markant från plasternas med avseende på formbarhet och vattentålighet.

Denna avhandling undersöker hur supramolekylära interaktioner kan användas för att skräddarsy egenskaperna hos cellulosa-baserade material genom att modifiera cellulosaytor eller styra hur cellulosa nanofibriller (CNFs) sätts samman. Huvuddelen av arbetet berör grundläggande studier kring interaktioner i vatten, men några materialkoncept och potentiella tillämpningar diskuteras.

Den första delen avhandlar hur spontan adsorption av xyloglukan eller polyelektrolyter kan användas för att modifiera cellulosa. Resultaten indikerar att xyloglukan adsorberar till cellulosa på grund av den ökade entropin hos vatten som frigörs från ytorna, vilket liknar den ökade entropin hos frigjorda motjoner som driver polyelektrolytadsorption. Adsorptionen av polyeletrolyter beror på cellulosans laddning upp till en viss gräns, varefter laddningstätheten endast påverkar adsorptionen i första lagret i en multilager formering.

Adsorption av latexnanopartiklar med en korona av polyeletrolyter, ger hydrofoba cellulosaytor med stark och töjbar, våt vidhäftning, om kärnans glasövergång sker vid lägre temperatur än omgivningens.

Syftet med den andra delen av avhandlingen är att förklara interaktioner mellan olika typer av cellulosa nanofibriller i närvaro av olika joner. Detta görs med en modell bestående av jon-jonkorrelation och specifika joneffekter, som kan användas för rationell design av vattentåliga och transparenta filmer av nanocellulosa. Tillsatsen av små mängder alginat skapar också interpenetrerande dubbla nätverk, och dessa nätverk leder till en synergi som förbättrar både styvheten och töjbarheten hos filmerna i vatten.

En nätverksmodell utvecklades för att förstå dessa material. Modellen klarar av att förklara hur egenskaperna hos fibrillnätverk beror av parametrar som fibrillernas geometri, nätverkets soliditet och friktionen som induceras av specifika joner. Med hjälp av nätverksmodellen och modellen för joninducerade interaktioner kan vi skapa filmer med våtstyrka som överträffar den hos många plaster, eller med en töjbarhet som är lämplig för hygroplastisk formpressning till vattentåliga och biologiskt nedbrytbara förpackningar. Filmernas transparens och vatteninnehåll, samt biokompatibiliteten hos cellulosa, gör dem lämpliga som biomaterial eller för bioelektronikapplikationer.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2019. p. 66
Series
TRITA-CBH-FOU ; 2019:19
Keywords
Adhesion, adsorption, alginate, assemblies, biodegradable, biomaterials, biopolymers, cellulose, cellulose nanofibrils, CNFs, gas barrier, hemicellulose, interfaces, ion-ion correlation, latex, layer-by-layer, metal-ligand complexes, montmorillonite, multivalent ions, packaging, PISA, polyelectrolyte multilayers, polyelectrolytes, polysaccharides, RAFT, renewable, specific ion effects, supramolecular, surfaces, sustainable, thin films, water-resilient, xyloglucan
National Category
Chemical Sciences Materials Chemistry Polymer Chemistry Physical Chemistry Nano Technology Paper, Pulp and Fiber Technology
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-248046 (URN)978-91-7873-161-9 (ISBN)
Public defence
2019-05-10, F3, Lindstedtsvägen 26, Stockholm, 14:00 (English)
Opponent
Supervisors
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20190411

Available from: 2019-04-11 Created: 2019-04-03 Last updated: 2019-04-11Bibliographically approved

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Engström, JoakimBenselfelt, TobiasWågberg, LarsCarlmark, AnnaMalmström, Eva

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